Optimization of Second Distillation Process of Nongxiang Cude Baijiu by Response Surface Methodology

In order to improve the quality of cude baijiu, the second distillation process was optimized. Cude baijiu of nongxiang baijiu was used as raw material, and the separation efficiency of fusel oil was taken as an evaluation index. The temperature, time and pressure of the second distillation were optimized by response surface design. The results showed that the optimum second distillation process conditions of cude baijiu were temperature 85.5 ℃, time 92.7 min and pressure 0.16 MPa. Under these conditions, the separation efficiency of fusel oil could reach 89.31%. Fusel oil content of second distillation baijiu was significantly lower than that of cude baijiu and cude baijiu stored for 2 years(P<0.05). The proportion of four esters in the second distillation baijiu was all within the ideal proportion of nongxiang baijiu of ethyl caproate, ethyl lactate, ethyl acetate and ethyl butyrate, its style remained unchanged, but the taste quality was improved. Therefore, the second distillation process technology provides a new method for rapid aging of cude baijiu.